Effect of A+ (A = Li, Na and K) co-doping on enhancing the luminescence of Ca5(PO4)2SiO4:Eu3+ red-emitting phosphors as charge compensator

Abstract

A series of Ca5-x(PO4)2SiO4:xEu3+ red-emitting phosphors were synthesized through solid-state reaction, and alkali metal ions A+ (A = Li, Na and K) were co-doped in Ca5(PO4)2SiO4:Eu3+ to improve its luminescence property. The impacts of synthesis temperature, luminescence center Eu3+ concentration and charge compensator A+ on the structure and luminescence property of samples were studied in detail. X-ray diffraction results indicated that prepared Ca5(PO4)2SiO4:Eu3+, A+ had a standard Ca5(PO4)2SiO4 structure with space group P63/m. Under the excitation of 392 nm, Ca5(PO4)2SiO4:Eu3+ phosphors showed a red emission consisting of several emission peaks at 593 nm, 616 nm and 656 nm, relevant to 5D0→7F1, 5D0→7F2 and 5D0→7F4 electron transitions of Eu3+ ions, respectively. Luminescence intensity and lifetime of Ca5(PO4)2SiO4:Eu3+ can be significantly enhanced through co-doping alkali metal ion A+, which play an important role as charge compensator. The results suggest that Ca5(PO4)2SiO4:Eu3+, A+ red phosphors with excellent luminescence property are expectantly served as red component for white light-emitting diodes excited by near-ultraviolet.